# std::ratio_equal

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< cpp‎ | numeric‎ | ratio

Defined in header `<ratio>` |  |
template< class R1, class R2 > struct ratio_equal : std::integral_constant<bool, /* see below */> { }; |  | (since C++11)

If the ratios `R1` and `R2` are equal, provides the member constant value equal true. Otherwise, value is false.

### Helper variable template

template< class R1, class R2 > constexpr bool ratio_equal_v = ratio_equal<R1, R2>::value; |  | (since C++17)

## Inherited from std::integral_constant

### Member constants

value [static] | true if R1::num == R2::num && R1::den == R2::den, false otherwise (public static member constant)

### Member functions

operator bool | converts the object to bool, returns value (public member function)
operator() (C++14) | returns value (public member function)

### Member types

Type | Definition
`value_type` | bool
`type` | std::integral_constant<bool, value>

### Possible implementation

    template< class R1, class R2 >
    struct ratio_equal : public std::integral_constant <
                                     bool,
                                     R1::num == R2::num && R1::den == R2::den
                                > {};

### Example

Run this code

    #include <iostream>
    #include <ratio>

    int main()
    {
        constexpr bool equ = std::ratio_equal_v<std::ratio<2,3>,
                                                std::ratio<6,9>>;
        static_assert(equ);
        std::cout << "2/3 " << (equ ? "==" : "!=") << " 6/9\n";
    }

Output:

    2/3 == 6/9

### See also

ratio_not_equal (C++11) | compares two `ratio` objects for inequality at compile-time (class template)

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